Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Considerable avalanche danger exists at all elevations due to wind slab, storm slab, and loose dry avalanche problems.  Dangerous avalanche conditions exist with natural triggered and human triggered avalanches likely today.  Cautious route finding and conservative decision making are essential.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Wind slabs will be likely on NW-N-NE-E-SE-S aspects in near treeline and above treeline areas.  Additional snow today with strong to gale force SW/W winds will continue wind slab development.  These wind slabs could be natural or human triggered and well over 2 feet deep in size with severe consequences.

    Look for blowing snow, cornice formation, and wind pillows.  Avoid steep wind loaded terrain and run out zones below wind loaded terrain.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Storm slabs will be likely on all aspects in near treeline and below treeline protected terrain.  These storm slabs could be up to 2 feet deep and may have trouble bonding to the old snow surface or within the storm snow.  Cold temperatures may further prolong the bonding process.  Periods of increased snowfall rates this morning may also add to instability.  Look for cracking around skis and any signs of cohesion within the storm snow.  Avoid slopes that show signs of unstable snow.   

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Loose dry avalanches are likely on all aspects in wind protected areas on slopes steeper than 35 degrees.  Most of these will occur in below treeline terrain but it's possible in other wind protected areas where unconsolidated storm snow exists.  These loose dry avalanches are expected to be small but could be large enough to carry a backcountry user into rocks or trees where injury could occur.  Terrain traps could also increase the consequences of a loose dry avalanche.

Avalanche Discussion

Observations were made and received yesterday from Tamarack Peak (Mt. Rose area), Negro Canyon (Donner Summit area), and Wheeler Ridge (Bear Valley area).  A wind slab avalanche was reported from Wheeler Ridge that was skier triggered and may have involved a cornice failure.  Strong SW winds were reported at all areas with varying amounts of snow available for transport.  Graupel was reported as the storm began on Donner Summit around 3:30pm. 

Regions covered